---
title: APEX Backend
emoji: 🏎️
colorFrom: green
colorTo: red
sdk: docker
app_port: 7860
pinned: false
license: apache-2.0
short_description: APEX race-engineer backend (FastAPI + LangGraph + Granite)
---

# APEX Backend on HuggingFace Spaces

This Space hosts the **APEX** race-engineer backend for the IBM SkillsBuild AI Builders Challenge May 2026 submission. The frontend lives at <https://apex-one-black.vercel.app>; this Space is the Python FastAPI backend it calls.

## Endpoints

| Method | Path | Purpose |
|--------|------|---------|
| GET    | `/healthz`              | container readiness probe |
| GET    | `/api/session-context`  | race-session tile feed |
| GET    | `/api/orchestration`    | LangGraph 6-node trace on canonical Sarah Reynolds fixture |
| POST   | `/api/audit-log`        | append-only Guardian audit log (JSONL + flock) |
| POST   | `/api/what-if-replay`   | byte-deterministic V2 cvxpylayers replay |
| POST   | `/api/analyze`          | end-to-end pipeline (JSON file-path input; legacy) |
| POST   | `/api/analyze-upload`   | end-to-end pipeline (multipart upload; wave-48) |

## Honesty surface

- Forecast engine: deterministic seasonal-naive baseline. Frozen TTM r2 wire is gated behind `APEX_ENABLE_TTM=1` Space env (see Phase 4 Day 4 G4 FAIL pivot in [`logs/day-04-g4.md`](https://github.com/StephenSook/apex/blob/main/logs/day-04-g4.md)).
- Narrator engine: OpenRouter Granite 4.1 8B when `OPENROUTER_API_KEY` is set; deterministic template floor otherwise. Honest engine surfaced in the per-node trace detail.
- Orchestration: deterministic 6-node Python state machine modeled on LangGraph semantics; not the `langgraph` package runtime. See [`docs/decision-log.md`](https://github.com/StephenSook/apex/blob/main/docs/decision-log.md) D-067.

## License

Apache 2.0. Repo: <https://github.com/StephenSook/apex>.